1. Field of the Invention
This invention relates to a calculator and more particularly to an educational calculator and method that solves a mathematical problem without displaying the answer, subtracts from the calculated answer a supposed correct answer introduced by the user, and indicates whether the resultant of the subtraction is equal to zero (a correct answer) or is unequal to zero (an incorrect answer).
2. Description of the Prior Art
Hand held calculators as exemplified by those employing an integrated circuit designated MM5737 and marketed by National Semiconductor Corporation of Santa Clara, Calif. are and have been available for some time. Such calculators have a keyboard including keys for affording input of decimal numbers and mathematical functions; the calculators also have numeric LED displays for displaying to the user the correct answer. These prior art calculators can be extremely simple and perform only arithmetic calculations or can be implemented to calculate and display logarithms, trigonometric functions, square roots, and virtually any mathematical relationship desired. Such calculators, moreover, can employ standard algebraic notation or reverse Polish notation.